Cellular coverage: If the app status bar shows "No Communication" or poor cellular reception (a single bar) it is likely that cell reception is insufficient for the call to go through. You can check cellular reception by entering Runner Mode and validate the app is updating via the status bar. Try calling the device again until it answers, as you would with a regular phone call that did not go through. If the device appears to answer, but is silent then the call most likely does not have sufficient cellular reception as well. You can try calling the device when it has adequate cellular reception and definitely has background noise to verify.

Phone number: Go to your settings, from the main Menu, and validate that your phone number is the number of the phone you are using

Blocked Caller ID: In order for an authorized number to be recognized and allowed to call, the number cannot be blocked. You can try calling another phone and see if your number shows up as blocked. To unblock your caller ID, please contact your phone carrier. (You can try calling your device directly, instead of using the app, and putting *82 in front of the device's phone number. If you are able to call using *82 then your phone number's caller ID is blocked.)

Third Party Provider: Some phones bind your phone number to a third party provider, such as Google Voice. You can try calling another phone and see what the number shows as. If it is a relay number, such as this that shows up on caller ID, it may be different every time. You would need to contact your phone carrier for this issue.

School Schedule: Verify that you are not calling during a time scheduled in the School Schedule.

Note: sometimes you may get a message saying your voicemail is not setup or the caller is not available. The reasons above apply to this case as well.